We are correlating the CMC with the motion of spin-labeled and specifically deuterated stearyl-CoA in solution, in micelles and ultimately in association with citrate synthase and biological membranes. A new method for determining CMC using ion specific electrodes has been developed. Deuterium NMR is used to determine relaxation times and we may be able to directly correlate NMR relaxation times with the line shapes of ESR spectra for suitable spin-labeled molecules. Knowledge of the solution properties together with spectral characteristics of acyl-CoA will enable us to properly interpret interactions with citrate synthase. We expect to demonstrate the nature of the interactions of acyl-CoA with citrate synthase and hope to interpret this data in terms of specific regulatory binding sites on this enzyme.